Problem: Some cars were parked in the hardware store parking lot. 1 more car parks at the hardware store. Now there are 28 cars in the parking lot. How many cars were parked at the hardware store at the beginning?
The number of cars parked at the store at the beginning is the difference of the number parked now and the number that came and parked earlier. The difference is $28 - 1$ cars. $28 - 1 = 27$ cars.